The present invention relates to a disk drive mechanism, and more particularly to a disk drive mechanism for centering and clamping a disk (hereinafter referred to as a "floppy disk") such as a flexible disk cartridge or a floppy disk in a disk drive unit.
One conventional disk drive mechanism will be described with reference to FIGS. 1 and 2. A spindle 2 is coupled to a motor shaft 1 rotatably suppported by a frame 13 and has an annular wall 2a on which there is disposed a flexible hub 4 supported by a support post 3 and composed of a plurality of segments 4a. A collet 5 is positioned concentrically on and above the flexible hub 4 with a spring 6 interposed therebetween. A holder plate 9 is disposed around the support post 3 and above the collet 5 with a spring 8 interposed between a washer 10 held against the plate 9 and an oilless bearing 7 coupled with the collet 5. The components disposed on and around the support post 3 are retained in place against removal by an E-washer or -retaining ring 11.
The portion encircled by A in FIG. 1 is shown at an enlarged scale in FIG. 2. As shown in FIG. 2, when the parts on the support post 3 are depressed into the spindle 2, an outer lower tapered portion 5a of the collect 5 abuts against and spreads an inner lower tapered portion 4a of the hub 4 to center a floppy disk 12 on an upper surface of the annular wall 2a of the spindle 2 and also to clamp the floppy disk 12 between a radially outward flange 4b of the hub 4 and the upper surface of the annular wall 2a.
With the conventional mechanism of the foregoing construction and operation, the tapered portions of the collet 5 and the hub 4, which are rigid bodies, are brought into interfitting engagement, and, due to their dimensional variations, no uniform pressure is imposed on the segments 4a of the hub 4 and the spindle 2. Therefore, the floppy disk 12 is not stably centered and clamped in position. Since the tapered interfitting portions are positioned below the surfaces which clamp the floppy disk 12, the segments 4a are tilted inwardly thereby reducing the centering accuracy. Ideally, the floppy disk 12 should first be centered and then clamped. With the prior arrangement, however, the floppy disk 12 is centered and clamped at the same time, resulting in a poor centering accuracy.